Friction and wear of 7075 aluminum alloy induced by torsional fretting

The torsional fretting wear tests of 7075 aluminum alloy flat against 52100 steel ball in dry condition were carried out on a new high-precision torsional fretting-wear tester. The kinetics behaviors and damage mechanism of 7075 aluminum alloy under different angular displacement amplitudes were investigated in detail. The results show that the torsional fretting running behaviors of 7075 aluminum alloy can be defined by three fretting regimes (i.e. partial slip regime (PSR), mixed fretting regime (MFR) and slip regime (SR)) with the increase of angular displacement amplitudes. In PSR, the damage occurs at the lateral portion of the contact zone with a slight annular shape. However, in MFR and SR, more severe damages are observed and the debris layer covers the wear scars. Friction torque and dissipation energy which are strongly dependent upon the imposed angular displacement amplitudes and presented in three stages were discussed in detail. The mechanisms of torsional fretting wear of aluminum alloy are mainly oxidative wear, abrasive wear and delamination in the three fretting regimes. In addition, the oxidative debris plays an important role during the torsional fretting wear processes.